Influence of solution chemistry on the removal of Ni(II) from aqueous solution to titanate nanotubes

In this work, adsorption of Ni(II) from aqueous solution to titanate nanotubes (TNTs) as a function of various water quality parameters was investigated under ambient conditions. The results indicated that the adsorption of Ni(II) to TNTs was strongly dependent on pH and ionic strength. A positive effect of humic acid (HA)/fulvic acid (FA) on Ni(II) adsorption was found at pH < 6.0, whereas a negative effect was observed at pH > 6.0. At low pH, the adsorption of Ni(II) was dominated by outer-sphere surface complexation or ion exchange with Na+/H+ on TNT surfaces, whereas inner-sphere surface complexation was the main adsorption mechanism at high pH. The TNTs are suitable material for the preconcentration of Ni(II) from large volumes of aqueous solutions.